On his way back from his last Hajj pilgrimage, Prophet Mohammad ordered a gathering at Khom, an oasis 64 km from Mecca, on the way back to Medina. He made a speech in which he appointed his cousin Imam Ali as his successor. Although both Shiite and Sunni sources accept the event, the latter interpret the prophet's speech as approval of Imam Ali as a friend not as a Caliph. This event remains the main dispute between two main sects of Islam to-date.Prophet Mohammad passed away two months later on May, 28. Right after his death, Arab tribal leaders gathered to appoint Abu-bakr as Mohammad's successor despite his final order. They could not get Imam Ali's allegiance. Omar threatened to burn his house down, an incident in which Ali's wife Fatemeh was seriously injured, causing miscarriage and her eventual death.